1. Field of the Invention
This invention relates to a shaped article of a polyurethane-urea spandex polymer which includes soft segments derived from a polyalkaneether glycol and hard segments derived from a certain hindered tertiary aralkyl diisocyanates. In particular, the invention concerns such an article made from spandex polymer which is formed by capping a polyalkaneether glycol with an .alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-p-xylylene diisocyanate and then extending the isocyanate-capped glycol with a specific mixture of diamines.
2. Description of the Prior Art
The art, for example Wittbecker, U.S. Pat. Nos. 3,507,834, and McMillin et al 3,549,596, discloses spandex filaments derived from a polyalkaneether glycol (e.g., polytetramethylene ether glycol, referred to herein as "P04G") that was capped with tertiary aralkyl diisocyanate (e.g., .alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-p-xylylene diisocyanate, referred to herein as "p-TMXDI") and then chain extended with a diamine (e.g., hydrogenated m-phenylenediamine, also known as 1,3-diaminocyclohexane, referred to herein as "HmPD"). Such spandex filaments have good tensile, whitenes and degradation resistance properties, but are deficient in heat settability and in resistance to swelling by certain solvents. Wittbecker and McMillin et al disclose that a plurality of chain extenders may be employed. However, neither discloses the particular combination of the three diamine chain extenders that are required in the practice of the present invention.
An object of the present invention is to provide a polyether-based spandxx polymer of the general type disclosed by Wittbecker and McMillin et al (i.e., P04G:pTMXDI:HmPD) that retains the good tensile characteristics of filaments made from the polymer, but also overcomes or significantly reduces its aforementioned shortcomings in heat set efficiency and solvent resistance.
Frazer et al, U.S. Pat. No. 2,929,803, discloses polyether-based spandex filaments made by reaction of a polyether glycol, a diisocyanate and a secondary amine. Poly(tetramethylene oxide) glycol is disclosed. A list of secondary diamines and a list of primary diamines with which the secondary diamines may be mixed are disclosed by Frazer et al in column 9, lines 55-74. Among the listed primary diamines are p-xylylenediamine and 1,4-diaminocyclohexane. Further, Frazer et al discloses that these diamines may be substituted with halogens, among other groups. However, tetrachloro-xylylenediisocyanates which are required in the spandex required for the present invention, are not disclosed by Frazer et al.
Although not concerned with polyether-based spandex polymers, Altau et al, U.S. Pat. No. 3,994,881, discloses polyester polyurethane-urea spandex filaments having improved resistance to degradation by ultraviolet radiation and chlorine-containing bleaches, in which the hard segments contain ureylene groups which are joined to "functionally non-aromatic" radicals, at least 25 mol percent of which are of the formula ##STR1## The polymers are prepared from a polyester glycol, tetra-halogenated diisocyanates and tetra-halogenated diamines. These tetra-halogenated diamines have been found by the present inventor to be useful as a minor constituent of the three-component diamine mixture employed as chain-extenders for the spandex of the shaped article of the present invention.